(1) Field of the Invention
The invention relates to multi cylinder internal combustion engines, such as, for use on boats, motorcycles, and the like.
(2) Brief Description of the Prior Art
It is well known that the speed at which a vehicle may be moved is highly dependent upon the power generated by the engine for that vehicle. Internal combustion, two cylinder engines fueled by a hydrocarbon fuel and mixture of air are common in vehicles, especially outboard motors for speed boats, and the like. It is always an objective of such engine design to incorporate air flow or intake systems which will permit maximum entry of air into the combustion cylinders. Quick adjustment of the air flow characteristics into the cylinders is very desirable to increase or decrease the speed of the boat In the past, butterfly valves have been used as a throttling system for air intake. However, such valves have been found to be rather undesirable when incorporated into outboard engines used in motorboat racing, where fine tuning is required for peak torque at specific rpm's.
Slide-type valves have been used in air intake systems for internal combustion engines as an alternative to butterfly valves. Typical of such slide valves is that design as shown in U.S. Pat. No. 4,454,537. Other slide valve designs are disclosed in U.S. Pat. No. 5,636,612. The slide-type valve design disclosed in the '612 patent is disadvantageous because it necessarily limits the size of the air ports through the valve assembly. This is because the design incorporates only one plate for slidable movements across the ports and the plate must be shifted in only one direction for opening of the ports and in the opposite direction for closing, or throttling, of the ports. It is highly desirable, for maximum air intake into the combustion cylinders, that the openings in the air intake assembly be as large as the openings of the cylinders.
The present invention addresses the problems associated with the designs of the prior art.